The present disclosure matter relates, generally, to panel illumination for interior paneling such as in vehicles, such as airplanes or automobiles and trucks. Various panel illumination designs providing either diffused soft lighting or decorative patterns of light, or both, are known in the art for use in these applications and others. As an example, as illustrated on the website of Diehl aerospace in Germany, http://www.diehl-aerospace.de/index.php?id=1345&L=1, exemplary aircraft cabin lighting can be used to avoid lighting glare, illuminate instruments and signs, and provide decorative patterns of light.
Light Emitting Diodes (LEDs), replacing fluorescent tubes, are paving the way for a completely new trend in vehicle interior lighting, such as aircraft cabin lighting, enabling new perspectives in cabin design and the potential to reduce significantly maintenance efforts and costs such as light source (incandescent and fluorescent) replacements.
FIG. 1 shows an example of a panel lighting arrangement 20 utilizing an LED holder 30 currently in use made of a suitable plastic material such as Acrylic Butadiene Styrene (ABS). The LED holder 30 extends into an opening in a lighting panel 22, which panel 22 may be made from a suitable light weight but sturdy plastic, such as an extruded polystyrene foam, and, for minimization of weight while retaining strength and structural integrity, may be formed in a honeycomb pattern, regular or irregular, with a portion of the panel 22 shown in FIG. 1 being a solid region of the honeycomb pattern. The panel 22 is sandwiched between a thin front film or skin 24 with a decorative surface, on the side viewed by the passenger when in use. The film 24 may be made of a polyvinyl chloride or the like. The panel 22 has a back film layer 26 on the side opposite from the viewed side, which can be made from a suitable plastic material, such as nylon, to give the panel overall strength and toughness, while retaining some flexibility without allowing the honeycombed foam material to crack or split.
Throughout this specification, for consistency and without limitation, these two sides of the lighting panel, as well as the orientation of elements of the LED holders will be referenced as the front (viewed) and back (reverse hidden) sides.
An individual LED light string 28 is held in a bushing 30, which bushing 30 may be inserted into the opening in the panel 22. The bushing 30 has an expanded cylindrical back portion 32, which may be ribbed to act as an insertion knob. The bushing 30 has a smaller diameter front portion 34 with a front end 36, having a front end opening 38. The interior of the bushing 30 back portion 32 and front portion 34 may be hollow and threaded with internal threads 44. A light pipe 40, in the shape of cylinder with a front end tapering to a light pipe rod, has external threading on the cylindrical portion engaging the interior threads in the bushing 30. The rod portion of the light pipe 40, which has a special light shaping surface terminal end portion 52, extends through the opening 38 in the bushing front portion 34 front end 36. The cylindrical portion of the light pipe 40 is also hollow and in turn receives the LED 50 at the end of LED string 28 containing suitable wiring and connectors to power the LED, select color for the LED and the like.
There are a number of problems with existing panel illumination systems, which include problems with establishing and maintaining proper positioning and alignment during installation, maintenance of positioning of the LED's 50 and/or light pipes 40 after installation, due to, e.g., vibration experienced in vehicular lighting applications, and problems in limited space available on the rear side of the panel, such as panels placed in positions in close proximity to a bulkhead or gauge housing wall or the like on the rear side of the panel 22.
Alignment and positioning of the LED 50 and light pipe 40 vis-á-vis the panel 22 is critical to the effectiveness and/or decorative and aesthetic effects of the lighting. Perhaps even more critical, especially to applications such as aircraft lighting, is the positioning of the terminal end 52 vis-á-vis the decorative front surface of the film 24 and alignment of the light pipe to the light source. As an example, alignment and positioning of the LED with respect to the light pipe can affect the amount of light emitting from the terminal end 52 of the light pipe 40. Positioning and alignment of the terminal end 52 of the light pipe 40 vis-á-vis the decorative film 24 decorative front surface can be critical to achieving the desired aesthetic effects and doing so consistently from panel to panel and vehicle to vehicle.
Installation requirements utilizing glue to fix the holder bushing 32 in the panel and allowing it to set prior to inserting the LED 50 and/or light pipe 40 are undesirable from a time aspect, a materials aspect, a cost aspect and a health aspect.
A requirement to remove burrs or chads, left from drilling a hole for a light pipe 40 extension 52 opening in the front decorative film 24, also is objectionable from a time standpoint, and if not done properly can result in partly or completely blocking the light exiting the light pipe 40 at the decorative side of the film 24.
Current assembly and installation practice also requires drilling holes in the panel 22 from the rear side at appropriate LED 50 location points in the panel 22 for a desired distribution and pattern of the LEDs. The prior art bushings 30 are then glued in place and after setting hollowed out from the rear side by drilling. Then a hole is drilled from the front side for the light pipe 40 to extend through, with this hole being hand cleaned followed by threaded insertion of the light pipe 40 and positioning of the light pipe terminal end 52. The light pipe 40 hole in the decorative film 24 and the holder bushing 30 must be in very tight registration. Such an installation process is rife with opportunities for misalignment and mis-positioning and hence labor intensive.
This present installation process is done due to an acquired experience of the installer, perhaps supplemented by touch with the installer on the back side of the panel reaching around to the front side. Such potentially hit and miss alignment and positioning in the current process is not desirable.
An LED 50 is installed by pressing into the holder bushing 30 that in turn, is affixed by gluing, as shown in FIG. 1.
Many of these same problems also can be encountered in utilizing the current LED holder bushings 30 in other applications, e.g., where there is no light pipe utilized, such as for diffused indirect lighting through illumination of the entire panel 22 viewed surface on the front film 24, with a distribution of LEDs in the panel, or the illumination of a gauge or gauge border with an LED light source.
In addition, the arrangement of FIG. 1 may be unavailable in cases where there is limited space on the back side of the panel 22. In many cases, the space available is not sufficient for the LED sleeve 28 to fit between the panel 22 and adjacent bulkhead or such structure.
Accordingly, there is a need in the art for an improved panel illumination light source holder arrangement that may be more efficiently and cost-effectively installed and used.